Device for receiving and dispensing variable liquid quantities

ABSTRACT

There is disclosed a device for receiving and dispensing variable liquid quantities, in particular of blood and blood serum, including a cylinder carrying an exchangeable pipette of a transparent material and a plunger shiftable hermetically sealed therein, said device being characterized in that the plunger carries a plunger rod guided concentrical in the cylinder, the free end of said rod extending out of said cylinder being bent Ushaped and merging in a handle portion provided with corrugations and extending along the outer periphery of the cylinder.

I United States Patent 1191 1111 3, 7

Sarstedt et al. Nov. 19, 1974 DEVICE FOR RECEIVING AND 2.289.677 7/1942 Perelson 215/47 DISP vARlABLE LIQUID 2,456,687 l2/l948 Domingueza 222/386 2,761,598 9/l956 Darlington 222/562 QUANTITIES 3,006,386 lO/I96l Greis .1 222/562 [76] Inventors: Walter Sarstedt, 3,236.423 2/1966 Marbach et al... 222/309 Numbrecht/Rommelsdorf; 3,248.950 5/l966 Pursell et all 222/309 HansJNeter Krause Hannover. 3325,06l 6/l967 Ellsworth r 1 1. 22/386 Hermann wism, 3337.095 8/l967 Marbaeh et al... .1 222 311 StuttgarLFeuerbach, a of Germany 3.465.925 9/1969 Bertolli .1 2235b] [22] Filed: 29,1972 Primary Examiner-Robert B. Reeves [21] APPL 284506 Assistant Examiner-H. Grant Skaggs Attorney, Agent, or FirmMcGlynn and Milton [30] A Fgg-eifiglApgication Priority Data {57] ABSTRACT 1 [972 2:22:; There is disclosed a device for receiving and dispensing variable liquid quantities, in particular of blood [52] us. Cl 222/386 222/562 and blood serum, including a cylinder carrying an ex- [511 In 6 11 I06 changeable pipette of a transparent material and a [53] Field of i 386 562 plunger shiftable hermetically sealed therein, said de- 222/563 4g' R i, 2; T vice being characterized in that the plunger carries a 5/47. 220/42 DIG plunger rod guided concentrical in the cylinder, the free end of said rod extending out of said cylinder [56] Rderences Cited being bent U-shaped and merging in a handle portion provided with corrugations and extending along the UNITED STATES PATENTS outer periphery of the cylinder. [97,017 11/1877 Colmet 222/309 2.175,?47 10/1939 Dodd 222/386 4 Claims, 4 Drawlng Figures PATENTL 33v 1 9 m4 SHEU 10? 2 PATENIEL HEY I 91974 SHEH 2 (IF 2 fly] DEVICE FOR RECEIVING AND DISPENSING VARIABLE LIQUID QUANTITIES This invention relates to a device for receiving and dispensing variable liquid quantities, in particular of blood and blood serum, including a cylinder carrying an exchangeable pipette of a transparent material and a plunger shiftable therein.

This device is to be suited for chemical laboratories and test institutions, namely everywhere where variable liquid quantities are desired to be taken from a storage and are desired to be dispensed to various vessels for effecting certain examinations. Such pipetting devices are in particular required for medical-technical examinations, in which the serum centrifugalized from the blood cake is drawn out of the centrifugalizing tube and is to be presented to a test vessel or some other test device for causing a specific reaction or a plurality of such locations.

A very simple primitive method of dispensing blood serum is to simply pour it out of the centrifugalizing tube. In doing so it cannot be avoided, however, that parts of the blood cake are taken along, which then later interfere the reaction. In the event the blood and thus the serum contains a virus, this treatment of infectious material is dangerous and, therefore, generally also not permitted.

A slightly improved method was to use a conventional pipette like it is frequently used in chemical tests for drawing the serum. The drawing then either was effected with the mouth, which again is prohibited in case of infectious material, or by means of a hose applied to the upper end of the pipette with a suction ball at the end of this hose. This method has the disadvantage that depending on circumstances prior to submerging the pipette in the serum the ball is compressed to a greater extent than corresponding to the volume of the serum available. Then air will be drawn in after completely drawing the serum, and this causes an injection of the serum within the pipette up to the hose and into the ball. lf infectious material is used, not only the pipette, but also the hose and the ball must first of all be cleaned, before the next serum sample can be taken from. But even in case of noninfectious material such operation errors are dangerous, since parts of a serum sample can get into the next and the following samples and can distort the test results thereof.

If on the other hand the suction ball is not sufficiently greatly compressed prior to submerging the pipette, not enough serum is drawn. The operation must then be repeated, with an according time loss.

Finally, metering devices are known in which a pipette of glass or the like is capable of being inserted exchangeable. Such a conventional metering device has the disadvantage, however, that it is adjusted unwariably to a unvariably detraction quantity, which also for many purposes is not enough. If a larger amount of serum is to be drawn by means of such a metering device and is to be dispensed to various test vessels or the like, this must be done in just as many consecutive operations. This procedure is very time-consuming and is insufficient in the modern medical-technical test procedure of hospitals, medical test authorities and the like.

When dispensing blood serum the following problem is to be observed also:

Even in the event the same quantity of blood is always taken from the patient, the quantity of serum standing over the blood-cake after centrifugalizing is rather greatly subject to variations from one case to the other.

It must thus be required of a good pipetting device that it can receive in a single stroke a smaller or larger amount of blood serum and permits the dispension to one or more test locations. In this regard the taking along of blood-cake is to be reliably prevented, without requiring all to much skill of the testing person. Furthermore, the serum to be drawn is to not be caused to turbulate unnecessarily and above all things is to not be passed through by following air bubbles. The metering device, furthermore, is to be constructed in such a way that in normal operation the drawn blood serum only fills the respectively applied pipette, but does not enter the cylinder arranged thereover. This requirement is in particular important for handling infectious material.

The simple operability, furthermore, requires that a good pipetting device can be served in one hand, so that the testing person has the other hand free for other work.

All foregoing requirements are fulfilled in an unobjectionable way by the pipetting device of this invention described hereinafter. According to the invention it is proposed that the plunger carries a plunger rod guided concentrical in the cylinder, the free end of said plunger rod extending out of the cylinder being bent Ushaped and merging in a handle portion provided with corrugations and extending along the outer shell of the cylinder.

The manipulation of this pipetting device is effected in a simple way such that the cylinder is held between the hand ball and four fingers, while the thumb engages in one of the corrugations of the handle portion. Prior to submerging the pipette applied to the cylinder the handle portion is brought into the lower limit positions by means of the thumb so that the plunger is disposed in its lower most position within the cylinder.

Then the lower opening of the pipette is submerged in the vessel with the liquid to be drawn. Then by moving upward the thumb which possibly passes over into the next lower corrugation of the handle portion, the handle portion and thus the plunger are moved slowly and continuously upwardly. The upward movement is controlled by observing the transparent pipette point, and it is terminated as soon as the desired liquid amount has been drawn.

After drawing the liquid the thumb engaging the handle portion is not moved further and the pipette device is taken out of the container with the pipette point. The liquid quantity contained in the pipette point can now be dispensed in one or more vessels available by moving downwardly again the thumb accordingly.

The device thus does not contain any resilient means like the conventional metering devices or the initially mentioned suction ball do, so that the operation of drawing and dispensing liquid can at any time be interrupted, above all things the liquid movements can be controlled very accurately. Also an absolute reliable manipulation is achieved by the fact that the cylinder of the pipetting device is firmly surrounded by one hand, and this manipulation prevents an undesired entering of air and also an unintended dripping out of liquid received.

It can be desired for many purposes to obtain a control over the amount of the liquid drawn and to dispense it generally uniform in a plurality of vessels. The pipetting device then according to the invention is provided with a graduation at the plunger rod which can be read at the upper edge of the cylinder.

instead the graduation according to the invention can also be provided outwardly at the cylinder. Then the reading is effected at an according mark at the handle portion.

Preferably in this regard it is proposed that the graduation at the cylinder at the same time is formed as a detent system and includes a plurality of axially consecutive annular grooves at the outer periphery of the cylinder, while the handle portion is formed resilient and is provided with a detent projection in the vicinity of its free end which engages the annular grooves consecutively in a locking fashion upon shifting the handle portion.

The annular grooves so to say correspond to the graduation of a pipette and permit the operator to exclusively direct the attention to the dispense opening of the pipette, which is of a high significance in particular when handling infectious material. The dosage, i.e. the dispension of generally equal amounts to various locations, simply is effected by feeling that the handle portion is shifted by means of the thumb respectively from one detent into the next lower one.

The exchangeable connection of the pipette to the cylinder is preferably effected in such a way that the cylinder has a smooth collar at its lower end with a overall circular cross section for applying a pipette. The end of the collar can either be formed circular cylindrical or slightly tapered. This type of attachment is in particular recommended for pipettes of a larger cross section and thus a larger volume.

But in order to be able to handle smaller liquid amounts also with the pipetting device, the cylinder preferably is provided at its lower end with a hollow cylindrical insert of a soft resilient material in which then a pipette of a smaller diameter can be inserted. For using such pipettes of various diameters can be held available having a uniform outer diameter but different inner diameters.

Finally it is also provided for according to the invention that the pipette point carries a graduation.

Furthermore, it is proposed that the device includes a cap of a soft resilient material which can be applied to the thin convergent tip of the pipette point and thus closes it in this way. Thereby the entire operation is greatly facilitated when extracting, storing and dispensing liquid, in particular blood in medical-technical laboratories and hospitals, as set forth hereinafter.

So for instance in hospitals a certain amount of blood is extracted from a patient by inserting a needle in a vein, and this blood is to be sujected to various tests of a chemical or physical nature. For each of these tests a smaller or larger amount of blood is required. The amount of blood extracted from the patient generally is presented directly after the extraction to a container, for instance a soaker tube, from which the respectively required partial quantity is taken for each test by means of pipettes. The amount of blood remaining in the soaker tube or the like after extracting the partial amounts then generally is stored for a certain period of time in order to be able to take a further partial amount for a renewed effecting of a reaction in case of a wrong performance of a reaction or in case of an unreliable outcome thereof.

For such purposes either disposal type pipettes or pipette devices have been used having a cylinder and a plunger and an appliable pipette point. In this regard the pipette points have a relatively small volume and serve to receive a small partial quantity which is required for a single test. For each test then a new pipette point must be applied to the pipetting device. Also for conserving the liquid rest not dispensed yet the container was required from which the partial quantities were taken by means of the pipette. While thus up to now a special container was required for conserving the blood extracted from the patient or the blood serum, now the entire liquid amount required for all tests is drawn by means of the pipette in the pipette point ap plied to it. Then the thin convergent tip at the lower end of the pipette point is closed with the cap and finally the pipette is taken off the pipette point. The liquid contained in the pipette point can now remain therein, the pipette point being erected by means of the accordingly formed cap or being inserted in an according holder. As soon as then one or more partial amounts are to be taken from the pipette point, the pipette is again applied to the upper end of the pipette point, the cap is removed from the lower end and the partial amount is presented to the test vessel provided for this purpose. This operation can be repeated several times. Of course, the discharge of partial amounts can be effected immediately after the first drawing of the liquid into the pipette point, prior to applying the cap.

Preferably in furtherance of the invention it is provided for that the cap for the convergent tip of the pipette point at the same time is formed as a closure plug for a centrifugalizing tube. This configuration and dimensioning of the cap permits to apply the pipette point to a centrifugalizing tube which is closed by the cap and thus is connected to it in a firmly standing fashion, said centrifugalizing tube in turn being able to be placed in a conventional soaker tube stand. For blood tests the amount of blood now extracted from the patient can be given into the centrifugalizing tube and can be centrifugalized for settling the plasma or the serum. In this regard the tube is provided in the usual fashion with a label which contains the name of the patient, the date of the extraction and possibly further data.

From this tube the entire plasma amount or serum amount is subsequently drawn by submerging the pipette point, and the pipette point is closed by the cap. Then the cap is applied to the tube, and thus it on the one hand provides the pipette point containing the liquid amount with a firm support, and on the other hand the association to the respective patient is insured. If a partial amount of the liquid is to be taken for a test, the pipetting device is applied, and after lifting the pipette point out of the cap, the plunger of the pipetting device is accordingly moved downward.

Basically any desired partial amount can be extracted also from the pipette point by means of a thin pipette submerged in it from upwardly.

Preferably it is proposed that the cap is made in one piece with the pipette point and is connected thereto through a fragile web. Preferably this fragile web is provided adjacent the upper opening rim of the pipette point. By this integral configuration of the pipette point and the cap not only is the manufacture simplified and rendered more economical, but also the manipulation is facilitated. For doing drawing the liquid into the pipette point the cap can still be connected integral with the pipette point. It is fractured only then and is applied to the lower slim convergent end of the pipette point.

Finally it is proposed to provide integral with the pipette point a plug connected to it through a thin pliable band for closing the pipette point. Here also the production is simplified and rendered economical. Also the manipulation is facilitated to the effect that the plug is available after taking off the pipette and must merely be pivoted in flexing the band and inserted in the open ing of the pipette point. If then liquid is to be taken from the pipette point again, the plug is removed, but it is not lost, rather it is suspended undetachable at the upper rim of the pipette point.

The invention is explained in closer detail hereinafter by ways of example in referring to the drawings. in the drawings:

FIG. 1 is a part sectional side elevation of a pipetting device according to the invention with an applied pipette point closed by a cap;

FIG. 2 is a part section of view of a modified embodiment of the device;

FIG. 3 is a pipette point similar to the pipette point in HO. 1, but including an upward closure plug and a lower closure cap, applied to a centrifugalizing tube in a soaker tube stand; and

FIG. 4 is a part elevation of view of the pipette point in FIG. 3, with an integrally formed cap prior to a fracturing thereof and with a closure plug.

The pipetting device 1 illustrated in FIG. l includes a cylinder 5 with a plunger 2 shiftable therein and guided hermetically sealed, said plunger being free to be shifted from a lower limit position up to abutment with the cover 7 which closes the cylinder 5. The plunger 2 carries a plunger rod 3 which is guided in a bore of the cover 7. This plunger rod is bent U-shaped outside of the cylinder and merges in a handle portion 4 which is provided with corrugations for conveniently positioning the thumb and which extends along the outer periphery of the cylinder.

In the outer periphery of the cylinder annular grooves 8 are provided in uniform spacings which serve as detents for positioning the handle portion or the plunger. In the vicinity of the free end of the handle portion there is a detent projection 9 at the surface facing the cylinder, said projection respectively engaging in one of the annular grooves or resiliently engaging the outer periphery of the cylinder when the handle portion is axially shifted and sliding over the cylinder portion between two consecutive annular grooves.

On the collar 10 the enlarged neck 12 of a large volume pipette point 11 has been applied which is composed of glass or transparent plastic. The main portion 13 of this pipette point is cylindrical. The lower free end of the pipette point is drawn out as a relatively fine tip 14.

The pipette point ii is closed at the bottom side by a cap 15 of a soft resilient material which has a sleeve shaped portion l7 to be applied to the thin drawn out tip 14 of the pipette point 11 and a plate-shaped foot 16. The pipette point ll can thus be stored standing, after being taken off the pipette 1. ln FIG. 2 a modified embodiment in of the pipette has been illustrated. Here the cylindrical portion of the pipette is provided at the bottom side with a transverse wall 18a which has a central bore 19a. The plunger 20 can be moved downward until it engages this transverse wall. Below the transverse wall a collar 20a follows the cylinder. in which a hollow cylindrical insert 21a is inserted of a soft resilient material. This insert in a hermetically sealed fashion is seated in the collar and is held at the bottom side by a U-ring 220 which snaps into a groove at the free end of the collar 20a. The insert 2la accomodates a thin pipette 11a of glass like it is conventional in chemical laboratories. This pipette likewise has a cylindrical main portion with a graduation 23a and a thin drawn out point 14a.

FIG. 3 shows a pipette point 11b similar to the one in FIG. 1, applied to a cap 15b of soft resilient material which again is inserted in a centrifugalizing tube 29 which is disposed in a stand 31.

The upper opening of the pipette point 111; here is closed by a plug 27 which is integrally connected to the upper portion 12b to a web 28. Also the pipette point 11b has a graduation 23bwhich permits a reading of the originally extracted volume as well as a uniform dispension;

At the bottom portion the pipette point 11b is closed by a cap 15b which at the top side contains a collar 17!) for receiving the drawn out tip 14b of the pipette point 11b and at the bottom side is formed as plug 25 for the centrifugalizing tube 29. The collar 17b is surrounded concentrical by a further collar 24 which facilitates manipulation and forms an abutment for the upper edge of the centrifugalizing tube 29. The centrifugalizing tube is provided with a marking label 18.

ln FIG. 4 the upper end of the pipette point 11b has been illustrated shortly after the production, wherein the cap 15b is integrally connected through a fragile web 26 to the reinforced upper rim 12b of the pipette point 11b. Also the plug 27 is made integral with the pi pette point 111;, which is connected to the reinforced upper rim 12b of the pipette point to a small flexible band 28.

We claim:

1. A device for receiving and dispensing variable quantities of liquid such as blood and blood serum, said device comprising: a cylinder, a plunger disposed within said cylinder in hermetically sealed sliding relationship with said cylinder, a plunger rod extending out of the top end of said cylinder and in a U-shape to define a corrugated handle portion resiliently engaging the outer periphery of said cylinder, at least one of said cylinder and said plunger rod having graduations thereon, a smooth collar disposed at the bottom end of said cylinder and defining an opening therein, and a pipette having an upper end for frictionally engaging said collar and a lower end defined by a thin drawn out tip, said graduations including a plurality of axially spaced annular grooves extending about said cylinder, said handle including a detent projection which may be disposed in any one of said grooves upon axial movement of said handle portion.

2. A device for receiving and dispensing variable quantities of liquid such as blood and blood serum, said device comprising: a cylinder, a plunger disposed within said cylinder in hermetically sealed sliding relationship with said cylinder, a plunger rod extending out of the top end of said cylinder and in a U-shape to deline a corrugated handle portion resiliently engaging the outer periphery of said cylinder, at least one of said cylinder and said plunger rod having graduations thereon, a smooth collar disposed at the bottom end of said cylinder and defining an opening therein, a pipette having an upper end for frictionally engaging said collar and a lower end defined by a thin drawn out tip, said graduations including a plurality of axially spaced grooves extending about said cylinder, said handle including a detent porjection which may be disposed in any one of said grooves upon axial movement of said handle portion, and a closure cap of soft resilient material for hermetically sealing said thin drawn out tip of said pipette, said closure cap having an upwardly extending collar for receiving said thin drawn out tip, said 

1. A device for receiving and dispensing variable quantities of liquid such as blood and blood serum, said device comprising: a cylinder, a plunger disposed within said cylinder in hermetically sealed sliding relationship with said cylinder, a plunger rod extending out of the top end of said cylinder and in a U-shape to define a corrugated handle portion resiliently engaging the outer periphery of said cylinder, at least one of said cylinder and said plunger rod having graduations thereon, a smooth collar disposed at the bottom end of said cylinder and defining an opening therein, and a pipette having an upper end for frictionally engaging said collar and a lower end defined by a thin drawn out tip, said graduations including a plurality of axially spaced annular grooves extending about said cylinder, said handle including a detent projection which may be disposed in any one of said grooves upon axial movement of said handle portion.
 2. A device for receiving and dispensing variable quantities of liquid such as blood and blood serum, said device comprising: a cylinder, a plunger disposed within said cylinder in hermetically sealed sliding relationship with said cylinder, a plunger rod extending out of the top end of said cylinder and in a U-shape to define a corrugated handle portion resiliently engaging the outer periphery of said cylinder, at least one of said cylinder and said plunger rod having graduations thereon, a smooth collar disposed at the bottom end of said cylinder and defining an opening therein, a pipette having an upper end for frictionally engaging said collar and a lower end defined by a thin drawn out tip, said graduations including a plurality of axially spaced grooves extending about said cylinder, said handle including a detent porjection which may be disposed in any one of said grooves upon axial movement of said handle portion, and a closure cap of soft resilient material for hermetically sealing said thin drawn out tip of said pipette, said closure cap having an upwardly extending collar for receiving said thin drawn out tip, said closure cap having a shoulder disposed radially outwardly from said collar, said closure cap having a plug portion extending downwardly from said shoulder and disposed radially inwardly from said shoulder for being disposed in a tube for sealing the tube.
 3. A device as set forth in claim 2 wherein said cap is integrally connected to said pipette through a fragile web.
 4. A device as set forth in claim 2, including a plug for closing the upper end of said pipette, said plug being integrally connected to said pipette through a flexible band. 